This invention relates to an improved cartridge case for containing a disk-shaped data recording medium for recording and reproducing data such as documentary files and images and to be inserted into a recording/reproduction device. In another aspect, the present invention also relates to a structure on such a cartridge case by means of which a recording/reproduction device can distinguish a compatible cartridge from a non-compatible case.
In general, a cartridge case for containing a disk-shaped data recording medium (hereinafter referred to simply as a disk) is provided with a window such that a part of the disk contained therein is exposed so that an axis of rotation and a read/write head of a recording/reproduction device can touch specified areas of the disk surface. Such a window is usually provided with a shutter which is slidably attached to the cartridge case and can be opened and closed. Since a shutter for this purpose must be light and strong, use is usually made of a thin metallic plate while a plastic material is usually used for the cartridge case because molding can be effected easily. When a shutter and a cartridge case with different hardness are used in combination together, however, edge sections of the shutter come into contact with and scrape the softer surface of the cartridge case as the shutter is opened and closed. The plastic pieces thus scraped off from the surface of the cartridge case may fly through the aforementioned window and become attached to the surface of the disk. Not only will such pieces affect the recording and reproduction signals when the disk is used for recording and reproduction but they may also enter between the axis of rotation and the bearing on the recording/reproduction device to prevent the normal rotary motion of the disk. It is therefore one of the objects of the present invention to provide a cartridge case with which friction can be reduced when the shutter is opened and closed so as to prevent the generation of small plastic pieces, thereby improving the recording and reproduction characteristics of the disk contained therein.
In another aspect, the present invention is addressed to the problem of compatibility between a disk and a recording/reproduction device. Since cartridge cases containing disks have different shapes and there are many types of driving mechanisms for disks, it is not always a simple matter to examine compatibility between a disk and a device which accepts it. If a non-compatible cartridge case is erroneously inserted into a device, the cartridge case itself or the internal structure of the recording/reproduction device may be damaged. In the past, however, this problem has not been considered seriously. It is therefore another object of the present invention to provide a cartridge case having a structure by which compatibility with a device which accepts it can be easily and reliably ascertained such that damage to the cartridge case and/or the internal structure of the device can be prevented.